• The diference of wall elements state including the FRF function 

    ?Ó?TOWSKI, M; Kalaczynski, T; Castaneda Heredia Leonel F.; Martinod R, R.M. (Publisher PGUAS, 2013-01-01)
    The recommendation of the PN - B-03002 norm shows a need of quality control of wall elements production, and classified them as elements of category I or II